REQUEST SENSE
7. ATAPI Packet Command Specification
SONY AIT-1Turbo drive SDX-460V series Ver.1.0
7-63
Deferred Errors
Error code 70h indicates that the “Check Condition” status returned is the result of an error or exception condition
on the I/O process that returned the “Check Condition” status. This includes errors generated during execution of
the command by the actual execution process. It also includes errors not related to any command that are first
observed during execution of a command. Examples of this latter type of error include a servo-mechanism, off-
track errors, and power-up test errors.
Error code 71h (deferred error) indicates that the “Check Condition” status returned is the result of an error or
exception condition that occurred during execution of a previous command for which “Good” status has already
been returned. Such commands are associated with use of the Immediate bit, with some forms of caching, and
with multiple command buffering. Devices that implement these features are required to implement deferred error
reporting.
The deferred error may be indicated by returning “Check Condition” status to the Host as described below. The
subsequent execution of a REQUEST SENSE command shall return the deferred error sense information. If an
I/O Command terminates with “Check Condition” status and the subsequent sense data returns a deferred error,
that I/O command shall
not
have been executed. After the Device detects a deferred error condition, it shall return
a deferred error according to the rules described below:
1. If a deferred error can be recovered with no external system intervention, a deferred error indication shall not
be set unless required by the error handling parameters of the MODE SELECT command. The occurrence of
the error may be logged if statistical or error logging is supported.
2. If a deferred error can be associated with a particular function or a particular subset of data, and the error is
either unrecovered or required to be reported by the mode parameters, a deferred error indication shall be
returned to the Host.
Deferred errors may indicate that an operation was unsuccessful long after the command performing the data
transfer returned “Good” status. If data that cannot be replicated or recovered from other sources is being stored
using buffered write operations, synchronization commands should be performed before the critical data is
destroyed in the Host. This is necessary to be sure that recovery actions can be taken if deferred errors do occur
in the storing of the data.
